My 18 yo AS went to an outpatient program 3 times a week also. He went because that was a requirement for him to live at home. Once he figured out that the program was testing him for Opiates instead of the more sensitive test for his DOC Oxycontin, he started using also. Once I became aware that there were different tests for different drugs, etc. I purchased a 12 panel drug test. It became apparent that he was still using when I started testing him every 2 days.
He is now in a residential rehab because that is a requirement for him to be able to live at home. He would not have gone on his own. He did admit to needing help, but I can tell from his attitude that he is still not recovering. He is not using, but he is not recovering. However, that is and always will be a boundary for him to be able to live at home. No drugs allowed!
One thing that somebody told me is that he is still learning tools to use when he is ready.